Fatal error: Uncaught Error: Interface 'Ratchet\MessageComponentInterface' not found in /home/soh-works/www/websoket-sample/vendor/cboden/ratchet/src/Ratchet/Server/FlashPolicy.php:16 Stack trace: #0 {main} thrown in /home/soh-works/www/websoket-sample/vendor/cboden/ratchet/src/Ratchet/Server/FlashPolicy.php on line 16